The invention relates to an apparatus for pumping fuel from a tank to the internal combustion engine of a vehicle, as is known from the German Utility Model DE-GM 91 01 313. The known apparatus has a compression spring-loaded nozzle-shaped body that opens an additional flow cross section starting at a particular pressure in the return line from the internal combustion engine in order to reduce the delivery output of the jet pump. Since the nozzle-shaped body, because it opens in both directions, can be continuously flowed through, it is possible for fuel to flow back into the return line.
Furthermore, U.S. Pat. No. 4,503,885 has disclosed using a ball which functions as a check valve in the return line and is acted on by spring force. Since the ball is disposed in an additional space, the known jet pump is relatively large in size.
The apparatus according to the invention for pumping fuel from a tank to the internal combustion engine of a vehicle has the advantage over the prior art that with a compact construction, it prevents a return flow of fuel into the return line and at the same time regulates the pressure in the return line. As a result, the jet pump begins to deliver fuel at very low return quantities. At the same time, the through flow cross section at the closing member, which depends on the return quantity in the return line, produces a delivery quantity of the jet pump which depends on the return quantity.
Additional advantages and advantageous improvements of the apparatus according to the invention for pumping fuel from a tank to the internal combustion engine of a vehicle ensue from the dependent claims and the specification.
It is particularly advantageous if the spring loading the closing member is designed in such a way that the closing member lifts off from its sealing seat only when the system pressure for the engine has been reached. This permits the elimination of the pressure regulator normally required in the system of the internal combustion engine.